Feb 13th/14th 2012 Snow/ice Threat

Vanster67 wrote:Morning all. Noticed the 6z Nam and GFS were not as good as the run before. NAM still had a couple of inches for the plateau. Any ideas on whether or not this might be a Nowcast system? Hope so. Looking for a little extra! OHX had me at 70% sleet/snow mix for monday night. Now they changed it to 60% rain/snow. I also noticed that NW TN is under a winter Storm Watch. 12 degrees this morning! Anyone know the LINK for the African Weather Man Blog

yeah vann, winter storm watch out just 15 miles to my west, 12 miles to my north of me... so hopefully i can get a good 2 possible 3 inches here in jackson... see what happens

It is just the 6z right now but also the 12z NAM isn't looking so hot. I hope this isnt a trend.

MRX says some icing and an inch or so of snow is possible before it turns to rain.

.LONG TERM...(MONDAY THROUGH SATURDAY)...COLD SURFACE RIDGE OVER
FORECAST AREA BEGINS TO MODERATE MONDAY ALTHOUGH DRY AIR MASS WILL
KEEP DEW POINTS IN THE TEENS. HIGHS ABOUT 10 DEGREES WARMER THAN
TODAY. CLOUDS BEGIN TO INCREASE IN THE AFTERNOON AS NEXT SYSTEM
DEVELOPS OVER THE SOUTHERN PLAINS AND SPREADS MOISTURE NE. MONDAY
NIGHT CLOUDS WILL THICKEN AND LOWER WITH PRECIPITATION SPREADING
INTO THE PLATEAU AND SOUTHEAST TENNESSEE. TEMPERATURES WILL DROP TO
NEAR FREEZING AS PRECIPITATION BEGINS. A MIXTURE OF PRECIPITATION
TYPES IS POSSIBLE MONDAY NIGHT AND TUESDAY MORNING AS THE SYSTEM
MOVES EAST. A FEW HUNDREDTHS OF ICING AND AN INCH OR SO OF SNOW IS
POSSIBLE OVER THE FORECAST AREA TUESDAY BEFORE THE ATMOSPHERE WARMS
AND PRECIPITATION CHANGES TO ALL RAIN. WILL HIGHLIGHT THIS SYSTEM IN
THE HAZARDOUS WEATHER OUTLOOK. FRONTAL BOUNDARY WITH THIS SYSTEM
STAYS ALONG THE GULF COAST AND THEN REINFORCING HIGH PRESSURE
BUILDS BACK OVER THE TN VALLEY AND SOUTHERN APPALACHIANS WEDNESDAY.
BREAK IS ONLY TEMPORARY AS A SECOND STRONGER SYSTEM BRINGS SHOWERS
INTO THE REGION THURSDAY AND FRIDAY. HIGH PRESSURE BRINGS DRYING
TREND FOR THE WEEKEND.

Meanwhile as Bruce Mentioned Meg has WSW out

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE MEMPHIS TN
405 AM CST SUN FEB 12 2012

...WINTER STORM APPEARS LIKELY FOR PARTS OF THE MIDSOUTH MONDAY
AFTERNOON AND EVENING...

.INCREASING MID LEVEL MOISTURE WILL OVERSPREAD THE MIDSOUTH ON
MONDAY MORNING WITH VERY DRY AIR REMAINING IN PLACE NEAR THE
SURFACE. AS THE ATMOSPHERE CONTINUES TO MOISTEN MONDAY AFTERNOON...
PRECIPITATION WILL WORK ITS WAY DOWN TO THE SURFACE...GRADUALLY
OVERCOMING THE DRY AIR. AS IT DOES SO...TEMPERATURES WILL COOL AND
SUPPORT SNOW BY LATE MONDAY AFTERNOON.

WARMER MID LEVEL AIR WILL THEN BEGIN TO WORK NORTH MONDAY EVENING
WITH A TRANSITION FROM SNOW...TO A WINTRY MIX...TO DRIZZLE OR
FREEZING DRIZZLE BY MIDNIGHT IN MOST LOCATIONS.

ARZ028-MOZ113-115-TNZ001>004-019>021-048>051-122200-
/O.NEW.KMEG.WS.A.0001.120213T2200Z-120214T0600Z/
MISSISSIPPI-DUNKLIN-PEMISCOT-LAKE-OBION-WEAKLEY-HENRY-DYER-GIBSON-
CARROLL-LAUDERDALE-TIPTON-HAYWOOD-CROCKETT-
INCLUDING THE CITIES OF...BLYTHEVILLE...KENNETT...
CARUTHERSVILLE...UNION CITY...MARTIN...DRESDEN...PARIS...
DYERSBURG...HUMBOLDT...MILAN...HUNTINGDON...COVINGTON
405 AM CST SUN FEB 12 2012

...WINTER STORM WATCH IN EFFECT FROM MONDAY AFTERNOON THROUGH
MONDAY EVENING...

THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A WINTER STORM
WATCH...WHICH IS IN EFFECT FROM MONDAY AFTERNOON THROUGH MONDAY
EVENING.

* SNOW/SLEET/ICE ACCUMULATIONS...2 TO 3 INCHES OF SNOW. SOME SLEET
AND FREEZING RAIN MAY MIX IN MONDAY EVENING. LIGHT ACCUMULATIONS
OF SLEET AND ICE ARE POSSIBLE.

* TIMING...SNOW WILL BEGIN AROUND 3 PM AND CONTINUE THROUGH EARLY
MONDAY EVENING. SNOW MAY BE HEAVY AT TIMES BY EARLY EVENING.
SNOW WILL THEN MIX WITH SLEET AND POSSIBLY FREEZING RAIN DURING
THE EARLY EVENING BEFORE DIMINISHING TO DRIZZLE OR FREEZING
DRIZZLE AROUND MIDNIGHT.

* IMPACTS...TRAVEL CONDITIONS WILL BE TREACHEROUS MONDAY EVENING AS
ROADWAYS BECOME SNOW COVERED AND SLICK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.
CONTINUE TO MONITOR THE LATEST FORECASTS.

&&

$$

BORGHOFF

Im sure Dyersburg wx is plent happy about this

So it should be about 1-2 inches for middle tennessee with some icing.

Adam2014 wrote:So it should be about 1-2 inches for middle tennessee with some icing.

Its a very close call and this could easily wind up being nothing but a rain event for middle and east TN. Just wanted to put that possibility out there so people are not shocked if they see nothing but rain. That said its not that normal for MRX to mention accumulations before they put out a winter product. This one is a forecasters nightmare though.

This is a sounding from the 6zgfs for the Knoxville area at hr 54

We need the models to trend colder right now...

This will be a nowcast situation for sure we are not going to know for sure what is going to happen until tommrow afternoon.

Im sure Dyersburg wx is plent happy about this



Still a little unsure about this but after this winter just being under a WSW is awesome.

I borrowed this from another Chattanooga poster from another site. seems we may have a few hours of fun if I'm able to see it.

Thanks from Cyclogent:

6z NAM bufkit analysis for KCHA

Tuesday 1am - very light snow begins
Tuesday 2am - accumulating snow begins - DGZ saturated, entire column below freezing
Tuesday 3am - accumulating snow - DGZ saturated, entire column below freezing
Tuesday 4am - accumulating snow begins to mix with sleet, DGZ begins to dry out, EWL 40mb deep w/max temp of 1.4C
Tuesday 5am - liquid precip (ZR, valleys and higher elevations), DGZ dried out, EWL 80mb deep w/max temp of 2.5C
Tuesday 6am - liquid precip (R valleys, ZR higher elevations), DGZ dry, EWL 110mb deep w/max temp of 4.0C
Tuesday 7am thru 9am - very light rain or drizzle valleys, very light freezing rain or freezing drizzle higher elevations becoming all drizzle with temps above freezing areawide by 9am

Verbatim, 6z NAM has 0.12" precip in form of snow, 0.03" in the form of sleet, and then 0.05" liquid in the form of rain or ZR. Storm total 0.20". As I mentioned earlier, the NAM tends to be dryish with precip. (the HPC QPF forecast has 0.30" storm total precip this area). Also WAA events tend to start a bit earlier than modeled so don't be surprised if this begins an hour or two earlier then listed above, say around midnight.

12zGFS is definatley beginning on a better note, thank the lord.

EDIT: Nevermind that was a terrible run.

It will be interesting to see what OHX does...its their move!

According to their AFD, they are not hyping this up much at all.

lol...and no that is not racist...I just think the lady is way cool

Toot wrote:


lol...and no that is not racist...I just think the lady is way cool

lmao

Nothing is set in stone right now. But at this point I will be lucky to see a dusting.

Im gonna go ahead and give this one a shot later on tonight. I like to try and give a forecast for such a challenging system. Probably try and have it done around 8pm

MEG discussion

THE MAIN FACTOR DRIVING THIS WINTER STORM WILL BE THERMAL
PROFILES. OVERALL...THE MODELS HAVE NOT CHANGED A WHOLE LOT WITH
THIS IN THE PAST FEW DAYS. THEY CONTINUE TO ADVERTISE A
SUBFREEZING SOUNDING NORTH OF I-40...EXCEPT AT THE SURFACE...
MONDAY AFTERNOON AND VERY EARLY EVENING. SOUTH OF THERE...IT
LOOKS LIKE 850 MB TEMPS WILL HOVER NEAR 0C MAKING FOR MORE OF A
SNOW/SLEET OR SLEET/RAIN MIX DEPENDING ON HOW MUCH SURFACE TEMPS
CAN COOL AS PRECIP BEGINS. SLEET AND RAIN WILL SIGNIFICANTLY
REDUCE OVERALL ACCUMULATION POTENTIAL. HOWEVER...IN THE AREAS
WHERE ALL SNOW IS FORECAST INITIALLY...NAMELY NORTHEAST ARKANSAS
THROUGH NORTHWEST TENNESSEE...2 TO 4 INCHES SHOULD FALL QUICKLY
BETWEEN ABOUT 20Z-02Z. SNOW WILL BE HEAVY AT TIMES IN THESE AREAS
GIVEN MOISTURE AND OMEGA FIELDS. GROUND TEMPS ARE COOL ENOUGH THAT
SNOW SHOULD START STICKING IMMEDIATELY. FURTHER SOUTH ALONG THE
I-40 CORRIDOR...LOWER AMOUNTS OF BETWEEN 1/2 TO 1 INCH ARE
FORECAST DUE TO MORE OF A SLEET MIXTURE. FURTHER SOUTH ACROSS
NORTHERN MISSISSIPPI...BOUNDARY LAYER CONDITIONS DO NOT APPEAR
CONDUCIVE FOR MUCH ACCUMULATION.

BY EVENING...THE THERMAL PROFILES WILL BE WARMING AS MOISTURE
CONTINUES TO INCREASE. PRECIPITATION WILL TRANSITION TO A MIX
EVERYWHERE EARLY MONDAY EVENING AND ALL RAIN BY LATE MONDAY
EVENING. SOME LOCATIONS OVER THE FAR NORTH/WEST CWA MAY REMAIN
NEAR FREEZING AT THE SURFACE LEADING A THREAT OF SOME FREEZING
DRIZZLE.

BECAUSE AT LEAST 2 INCHES OF SNOW ARE FORECAST NORTH OF THE I-40
CORRIDOR AND SLEET AND FREEZING RAIN MAY ALSO ACCUMULATE...DECIDED
TO ISSUE A WINTER STORM WATCH MONDAY AFTERNOON/EVENING FOR THOSE
AREAS. WILL PROBABLY NEED A WINTER WEATHER ADVISORY FOR THE REST
OF THE AREA AT SOME POINT.

Thanks DW...this is certainly a complex system with all modes of frozen precip and pure liquid type also. Then you have temp profiles going from favaorable to unfavorable and back to favorable again.

the 12z euro has 1 to 3 inches still for much of west tn, and getting into parts of mid tn... the euro has been very consistent with this. surface temps slightl cooler at that.

This is looking like a non event for folks east of far western tennessee. I mean theres still hope there but This is like the opposite of when we have cold air chasing the moisture. We have moisture chasing the cold air thats leaving so faster this storm moves in the better for snow and the longer that cold air can not move the better too.

I've saw these things go either way so many times. If it actually starts off as snow, especially enough to cover the ground, much better odds on a fairly wintry solution. If it does much in the way of raining it's hard to ever get much wintry precip going.

My most memorable event similar to this was in February 1993. It was a Friday morning that was supposed to have snow moving in that quickly changed to rain early in the morning. It never made the change over and I ended up getting 4 inches of snow out of it. That was the first snow of more than 1 inch for the entire 1992-1993 winter.

By looking at local AFD, Jackson is being pretty aggressive for snow in their area. MRX slightly less so.

My particular area is notorious for being very very slow to give up the surface cold air due to being surrounded on all 4 sides by peaks about 800-1000 feet higher than me.

JKL is talking about how their southern and eastern valleys might hold onto freezing rain for a long while, but they just aren't sure.

It was nice last year to actually not constantly have the issues with getting wintry precip in the area that I'd grown accustomed to the past 10 years.

This is a forecast put together with todays SREF and NAM models..this forecast is highly dependant on the temp profiles of those models. If they are off a hair it could make for big changes in the outcome...this will ultimately be a nowcast situation but it seemed to be a rough one so I thought I would give it a shot

Light snow...sleet and freezing rain accumulations will be possible across most of the state on Monday and Tuesday. Particularly concerned for the East TN valley where I think the most ice accumulations will be possible.

Looking at soundings and mostly SREF data it appears that a mixed bag of weather will move into the state from west to east. With very low dewpoints already in place precip will move into the area as Virga but as the column becomes saturated precip will start to fall in the form of snow.

The snow could fall at impressive rates at times in the western and southern parts of the state. At some point the snow will transition to wintry mix and then to rain over most of the state. I imagine the plateau and mountain regions of the state could pick up several inches of snow in a fairly quick fashion.

The east TN valley poses a unique threat for Ice accumulation in excess of more than .10 inches due to the nature of local topography. After some possible light accumulations of snow the cold air might become trapped in low lying valley areas and freezing temps could stick around for a longer period of time but meanwhile the upper atmosphere temps will warm to above freezing resulting in longer periods of ice accumulations on top of light snow accums. Light Ice accums appear likely for parts of East TN valley





EDIT: The light ice accumulations should read "likely" in the East TN valley.

I'm not sure if there is enough QPF while it's cold to get a moderate snow event anywhere outside of far NW Tennessee tbh. I will hold out hope you're correct though.